Artificial tooth



. G. FELDMAN HAL ARTIFICIAL TOOTH Filed Aug. 27, 1940 Max G. F ELD MAN BENJAMIN PaRLow Eatented Jan. 13, 1942 ARTIFICIAL TOOTH Max G. Feldman and Benjamin Perlow, Pittsburgh, Pa.

Application August 27, 1940, Serial No. 354,362

4 Claims.

The present invention relates generally to artificial teeth and is more particularly directed to bridge teeth, namely, to an artificial tooth which is adapted to be permanently and rlgidly'mounted in a bridge fixture which is designed to be permanently or removably positioned in the mouth.

More specifically, the type of tooth to which the present invention is directed is an artificial tooth formed of a suitable moldable composition, such as porcelain or like material, which tooth is provided with a metallic backing, 'the metallic backing serving as a supporting retainer for the artificial tooth and serving also as a part or element of a bridge or as a means for permanent attachment of the artificial tooth to a bridge or to a foundation in an abutment tooth.

It is the object of the present invention to provide a bridge tooth of this type which yields a highly aesthetic appearance. For this purpose the metal backing does not cover the lower third or the incisal portion of the tooth. This structural arrangement does not interfere with the translucency of that portion of the tooth and the tooth, therefore, retains its lustre and natural appearance. As an aid to the aesthetic appearance of the tooth, the backing and tooth are so constructed that, while the backing is firmly anchored in the tooth structure, no portion of the metal backing, preferably of gold or similarly suitable metal, is obvious on the exposed or labial or buccal side of the tooth. Moreover, it is an object to provide a backing of such design and construction as to simulate the anatomical contours of a natural tooth on its lingual surface, at the same time permitting such rotation as may be desired to achieve an overlapping effect to enhance the appearance of the restoration.

In actual installation and in use, it frequently happens that the porcelain portion of such a combined porcelain and metal tooth becomes fractured. In such event, it is desirable that the porcelain tooth be replaced without necessitating the removal of the bridge from the mouth or altering the metal supporting retainer for the replacement tooth. It is the object of the present invention to provide a tooth of this type in which this replacement of the porcelain tooth may be accomplished with great facility and without any substantial disturbance of the metal backing.

Another object of the present invention is to provide a bridge tooth of the type described which while absorbing its own stresses to which it is subjected during mastication, does not transmit any excessive stresses to abutment teeth. The

transmission of excessive stresses to such abutment teeth frequently causes the loosening of the bridge supports and on occasion also may cause harm to normal, healthy abutment teeth.

A further object of the present invention is to provide a bridge tooth of the type described which obviates food traps and makes the restoration highly hygienic not only because of the anatomical form of the replacement but also because the tissue-contacting surfaces are of glazed porcelain or the like and the gold or other metal backing is also accessible for a high polish.

Other objects of the present invention will become apparent to persons skilled in the art from the illustrative embodiment thereof appearing in the accompanying drawing and more specifically described in the present specification, it being understood that the invention may be embodied in a variety of teeth, both anterior and posterior, the present embodiment merely serving for illustration and not as a limitation upon the present invention.

In the drawing:

Figure 1 represents the lingual surface of the tooth;

Figure 2 represents a proximal surface of the tooth;

Figure 3 is a lingual proximal view of the tooth;

Figure 4 is a perspective view of the metal backing;

Figure 5 is an external view of the metal backme;

Figure 6 corresponds to Figure 2 with the metal backing removed therefrom;

Figure 7 corresponds to Figure 3 with the metal backing removed; and

Figure 8 is a sectional view of the tooth taken on the mesio-distal median line of the tooth.

Broadly stated, many of the aims of thepresent invention are accomplished by providing the artificial tooth with a metal backing on its lingual surface which covers approximately the middle third of the tooth and extending into the middle third of the lingual half of the proximal surfaces of the tooth. By means of this organizatlon broadly, the artificial tooth and metal backing are constructed to complement each other so that together they constitute a reproduction of the form of a natural tooth.

The tooth body I0 is generally cast or molded to the desired shape in a manner customary in the art. Such a preformed or precast tooth is then cut or ground or otherwise recessed to provide the desired cavity generally indicated by the reference ii for properly receiving the metal backing H. For this purpose, a horizontal lingually presenting trough is first cut into the middle third of the lingual surface of the tooth. The trough is preferably cut so as to provide an inner face 13 sloping approximately as indicated in Figure 8. Theincisal or occlusal wall ll of this trough-shaped cut may be approximately horizontal or. if desired, it may slope to a slight degree gingivally toward th lingual face of the tooth. The opposite or gingival wall l of the trough slopes gingivally from the inner face l3 thereof. This trough thus forms a tapering seat for the metal backing H. The inner face 13 of the trough is inclined toward the incisal or occlusal edge from the lingual toward the labial or buccal face of the tooth. The trough l2 extends at its opposite ends into the lingual halves of the middle thirds of the proximal surfaces as shown at I6 in Figure 6 of the drawing, these proximal extensions being substantially coextensive in depth with the main or lingual part of the trough.

A post hole I! is then drilled adjacent to the gingival wall I5 of the trough. While this post hole is preferably circular in cross-section, it may be of any other desired cross-section, e. g., oval or even rectangular or square. This post hole should preferably be inclined toward the incisal or occlusal edge and toward the labial or buccal face of the tooth, and preferably is inclined with its axis substantially parallel to a line a. bisecting the angle 17 formed by the projection of the incisal and gingival surfaces l4 and I5 of the trough. The axis of the post hole thus forms an acute angle with respect to the gingival wall I5 of the trough and provides a wedgeshaped section I1 between the gingival surface l5 and the incisal or occlusal wall portion of the post hole. This wedge-shaped portion II' increases in vertical depth from the lingual to the labial or buccal surfaces of the tooth. This angle of the post hole l6 permits clearance of the iingual-gingival portion of the tooth in seating the tooth on the backing when the tooth has been carved to saddle the ridge. This angle also permits the proper seating of the tooth in the socket when it is finished like a pontic for immediate restoration cases. This post hole 16 is also preferably disposed with its axis in the mesio-distal median plane of the tooth. By virtue of the substantial parallel relation existing between the post hole axis and the line a, upon seating the tooth upon the backing, the post of the latter (to be hereinafter more fully described) "serves as a guide within the post hole I! to provide for rectilinear movement of the tooth in the direction of the line a and so insure flush seating of the tooth upon the backing. The gingival wall l5 of the trough is then beveled off to form the inclined lingual surface l8, this beveling preferably extending to a point slightly beyond the gingival side of the post hole l6. This bevel tapers off on the proximal faces of the tooth so as to form a beveling IQ for the gingival edges of the proximal extensions l6 of the trough. A slight bevel 20 may also be applied to the free edge of the wall l4.

Preferably. as most clearly appears in Figures 7 and 8, the wedge-shaped section ll is slotted in the mesio distal median plane thereof to the depth of the trough 12, thus affording a notch or slot 30 disposed immediately beneath and in communication with the incisal portion of the post hole ll. In other words, the notch or slot 30 lies in the vertical plane of the axis of the post hole and serves as a socket for reception of an element of the backing to prevent any tendency for the latter to rotate about the axis of the post hole. Preferably, in order to facilitate and obtain a firmer and more secure engagement between the tooth and the backing, the notch or slot 30 is of a shape having side walls which diverge slightly toward the lingual face of the tooth.

The metal backing i I may be roughly described as being so shaped that it takes the form of that portion of the tooth which has been cut away as above described. Thus, it will be seen to comprise a main body portion 2| which is shaped complementally to and fits snugly into the main portion of the trough l2, this portion 2| constituting the thickest part of the metal backing. The portion 2i also is provided with the lateral projections or wings 23 which fit snugly into the proximal extensions ii of the trough. The portion 24 of the backing is somewhat thinner than the main body portion 2| and extends upwardly so as to cover the inclined lingual face I! and replace the material removed from that portion of the tooth.

A post 22 is formed integrally with this portion 24 of the backing and is adapted to project into the post hole 11. The post 22 is angularly inclined with respect to the portion 24 of the backing so as to be snugly accommodated within the post hole l1 when the backing is mounted in flush position upon the tooth. As appears most clearly in Figure 4, the post 22 is joined to the portion 2| of the backing by a fin-like element 3| which is adapted for projection into the notch or slot 30 and thus serves to prevent rotation of the post and backing as a unit about the axis of the post hole ll. This element 3| serves additionally as a reinforcing brace between the base of the inclined post and the main body of the backing.

The outer face of the backing plate II is shaped to form flush joints with the tooth and generally to conform it to the shape of a natural tooth. While in preferred form the backing II will be supplied ready-made with the desired lingdial contours, this backing may, of course, also be prepared by the dentist or technician or, if desired, a rail or post can be supplied which is designed to fit the post hole ll so that the remainder of the backing designed to fill the cutout portions of the tooth may be cast by the dentist or technician.

It will be understood, of course. that the metallic backing may be secured to the tooth in any suitable manner, as by cementing or otherwise. While reference has been made hereinbefore to cutting or grinding the backing-receiving recesses and surfaces in the tooth as a step or steps subsequent-to the initial formation of a complete tooth,'it will be understood that said recesses, including the aforementioned trough and post hole as well as the various surfaces immediately adjoining the same, may be formed in the tooth during the process of manufacture thereof. as by molding and baking the tooth with said recesses and surfaces preformed therein.

It will be understood, of course, that the invention is susceptible of various changes and modifications from time to time without departing from the real spirit or general principles thereof and it is, accordinglyfintended to claim the same broadly, as well as specifically. as indicated by the appended claims.

' aacaseo What is claimed as new and useful is:

1. In an artificial bridge tooth, in combination, a tooth body of porcelain or like moldable material having a relatively wide groove and a cutaway portion immediately above said groove in its lingual face, the incisal and gingival walls of said groove being so angularly related that a plane bisecting the angle formed by the projecting walls intersects the proximal median plane of the tooth at an acute angle, said body having a post hole projecting into the lingual face from the cut-away portion thereof at a point located immediately beyond the gingival side of said groove and with its axis substantially paralleling said bisecting plane aforesaid, and a backing fitting said groove and cut-away portion snugly with its perimetral edges flush with the surrounding surfaces of the tooth body, said backing having a relatively thick part and a relatively thin part closely engaging the groove and cutaway portion of the tooth, and a post integral therewith and extending from the thin part for accommodation within said post hole.

2. In an artificial bridge tooth,.in combination, a tooth bo'dyof porcelain or like moldable material having a relatively wide groove and a cutaway portion immediately above said groove in its lingual face, the inci's'aland gingival walls of said groove being so angularly related that a plane bisecting the angle formed by the projecting walls intersects the proximal median plane of the tooth at an acute angle, said 'body having a post hole projecting into the lingual face from the cut-away portion thereof. at a point located immediately beyond the gingival side of said groove and with its axis substantially paralleling said bisecting plane aforesaid, and a backing fitting said groove and cut-away portion snugly with its perimetral-edges flush with the sur-- rounding surfaces of the tooth body, said backing having a relatively thick part and a relatively thin part closely engaging the groove and cut-away portion of the tooth, and a postintegral therewith and extending from the thin part for accommodation within said post hole, the gingival wall of said groove being notched to provide a communicating slot between said groove and said post hole, and a reinforcing fin between said backing and its post adapted for reception in said slot.

3. In an artificial bridge tooth, in combination, a tooth body of porcelain or like moldable material having a relatively deep main groove in the middle third of its lingual face, said main groove being provided at its opposite ends with continuations in the shape of lateral recesses formed in the proximal faces of the tooth and extending linguo-buccally or linguo-labially thereof, the gingival edges of the recesses respectively formed in the proximal faces of the tooth being extended about the lingual face of the tooth along a line spaced gingivally from said main groove. the portion of the tooth body between said main groove and said lingually extended line of the lateral recesses being smoothly merged with the lingual surfaceof the tooth, said last-mentioned body portion of the tooth having a post-hole therein disposed with its axis extending substantially in a linguo-labial or linguo-bu'ccal direction, and a supporting backing for said tooth adapted to fit the same to complete the anatomical formation of the lingual surface of the tooth,

said backing having a relatively thick main body A portion and relatively thick lateral Wing-like elements respectively adapted for snug accommodation in the main groove and lateral recesses of said tooth body, the remaining portion of said backing being gradually reduced in thickness toward the gingival edge thereof to provid a flush relation with the surfaces of the tooth body, said backing having an integral post adjacent said gingival edge thereof for accommodations within said post-hole, said post and Wing-like elements being arranged in substantially parallel relation to facilitate assembly of the tooth body and backing by a substantially rectilinear motion of one with respect to the other in a labio or buccolingual direction.

4. In an artificial bridge tooth, in combination, a tooth body of porcelain or like moldable material having-a relatively thick gingival end part and a relatively thin incisal end part, said body having a relatively wide groove in the lingual face of the incisal part, and a cut-away portion in the thick part immediately adjacent said gro'ove, said thick part having a post hole opening into the cut-away portion thereof at a point located immediately beyond the gingival side of said groove with its axis directed from the lingual side toward the labial side of the tooth, and a backing fitting said groove and cut-away portion snugly with its perimetral edges flush with the surfaces of the tooth body, said backing having a relatively thick part and a relatively thin part closely engaging the groove and cut-away portion respectively, and a. post integral with the backing extending from the thin part and entering the post hole.

MAX G. FEIDMAN. BENJAMIN PERLOW. 

